The Hungarian economy ministry said the Moody's downgrade had "no basis because, despite all the external difficulties, in the past year-and-a-half there has been an expressly favourable change in most areas of the Hungarian economy".

Mr Orban has followed an unconventional policy of allowing Hungarian households to convert their mortgages - which were predominately taken out in foreign currencies, particularly the Swiss franc, prior to the 2008 financial crisis - back into Hungarian forint at the expense of the banks.